Instagram test and Instagram node fixes

This is my work on adding the Instagram tests. A few issues might need to be sorted. I'll make comments in-line detailing these.
@hindessm after a long debug session, I got a bit closer to finding the reason for the odd failures of the image-buffering test. It turns out that upon the failure of the "reports a failure when it fails to get subsequent user photos " test case, the node's outputType property survises the clean-up of the helper somehow?!  The scenario is very odd. During the buffering test, the code inside instagram.js (ie the node instance itself) believes that it is in "link" mode, however when printing out the state of instagramNode1 in the test the node's state is indeed "file" (ie buffer). I'm confused as to why this is happening. This fix smells to be the incorrect fix, however it does eliminate the issue.